Mills says cats appear to have an "anxious avoidant" attachment style. That means they do not care whether their owners are present or not.

Mills says dogs' attachment style is similar to that of children. They "love" their owners in the same way children love their parents.

According to KUSA-TV psychologist Max Wachtel, children with "anxious" attachment style will be stressed and uncomfortable whether their parents are close by or not. They will not see the parents as a source of emotional stability or as a soothing presence in their lives.

They will grow up and have difficulty attaching to other people, so forming friendly and romantic relationships will be difficult. They will also have problems with being manipulative and seeing other humans as a "provider of resources" or only as a "means to an end."